1. Field of the Invention
The present invention relates to an apparatus for detecting an abnormality of a pressurizing device in a hydraulically operated braking system.
2. Discussion of Related Art
JP-A-10-236294 discloses an example of such an apparatus for detecting an abnormality of a pressurizing device. This apparatus is adapted to detect an abnormality of a pressurizing device in the form of a vacuum booster (hereinafter referred to simply as xe2x80x9cboosterxe2x80x9d), and includes (1) a master cylinder pressure detecting device for detecting a hydraulic pressure in a master cylinder which is arranged to generate the hydraulic pressure corresponding to an output force of the booster provided to boost a brake operating force acting on a brake operating member; (2) a booster pressure detecting device for detecting a hydraulic pressure in a variable-pressure chamber of the booster; and (3) a diagnosing device for determining whether the booster is abnormal, on the basis of a relationship between the hydraulic pressure detected by the master cylinder pressure detecting device and the hydraulic pressure detected by the booster pressure detecting device.
The hydraulic pressure in the variable-pressure chamber of the booster changes towards the atmospheric pressure as the brake operating force is increased. Accordingly, the hydraulic pressure in the variable-pressure chamber increases with an increase of the hydraulic pressure in the master cylinder. When the booster is normal, the hydraulic pressures in the variable-pressure chamber of the booster and the master cylinder have a predetermined relationship, that is, are held within respective predetermined ranges. If these two hydraulic pressures detected by the master cylinder pressure detecting device and the booster pressure detecting device are not held within the respective predetermined ranges, it is possible to determine that the booster is abnormal. Thus, the determination as to whether the booster is abnormal or not is effected in the known booster-diagnosing apparatus, while the brake operating member is in operation.
However, the known booster-diagnosing apparatus disclosed in the publication identified above is not capable of detecting an abnormality of the booster while the brake operating member is not in operation. This is because the booster is activated only when the brake operating member is operated.
It is therefore an object of the present invention to provide an apparatus which is capable of detecting an abnormality of a pressurizing device in a hydraulically operated system, even while the brake operating member is not in operation.
The above object may be achieved according to any one of the following modes of the present invention, each of which is numbered like the appended claims and depends from the other mode or modes, where appropriate, to indicate and clarify possible combinations of elements or technical features. It is to be understood that the present invention is not limited to the technical features or any combinations thereof which will be described for illustrative purpose only. It is to be further understood that a plurality of elements or features included in any one of the following modes of the invention are not necessarily provided all together, and that the invention may be embodied without some of the elements or features described with respect to the same mode.
(1) A diagnosing apparatus for diagnosing a pressurizing device provided in a hydraulically operated braking system operated by a brake operating member, comprising: a hydraulic pressure detecting device operable to detect a hydraulic pressure which is a sum of a first fluid pressure generated by an operation of said brake operating member, and a second fluid pressure generated by an operation of the pressurizing device; and a diagnosing device operable to determine whether the pressurizing device is abnormal or not, on the basis of the sum of the first and second fluid pressures detected while the brake operating member is not in operation and while the pressurizing device is in operation.
In the diagnosing apparatus according to the above mode (1) of this invention, the pressurizing device is diagnosed on the basis of a hydraulic pressure which is a sum of the first and second fluid pressures which are detected by the hydraulic pressure detecting device while the brake operating member is not in operation and while the pressurizing device is in operation. While the brake operating member is not in operation, the first fluid pressure is not generated by the brake operating member, so that the hydraulic pressure detected by the hydraulic pressure detecting device is equal to the second fluid pressure generated by the pressurizing device, more precisely, the second fluid pressure corresponding to the operating condition of the pressurizing device. Accordingly, the diagnosing device can be diagnosed while the brake operating member is not in operation.
As indicated above, the hydraulic pressure detected by the hydraulic pressure detecting device while the brake operating member is not in operation does not include a fluid pressure generated by the brake operating member.
Where a booster is connected to the brake operating member, as described before, the first fluid pressure corresponds to an output of the booster which is adapted to boost the operating force acting on the brake operating member. Namely, the first fluid pressure corresponds to the brake operating force as boosted by the booster.
(2) A diagnosing apparatus according to the above mode (1), further comprising a vehicle speed detecting device for detecting a running speed of an automotive vehicle on which the hydraulically operated braking system, and wherein the diagnosing device includes a determining portion operable to determine whether the pressurizing device is abnormal or not, on the basis of the hydraulic pressure detected while the running speed of the automotive vehicle detected by the vehicle speed detecting device is lower than a predetermined first threshold value.
While the vehicle running speed is lower than the predetermined first threshold value, there is a low possibility that the brake operating member is operated. In other words, the first threshold value is determined so that the possibility of the brake operating member at a vehicle running speed lower than the first threshold value is low. Accordingly, the pressuring device can be diagnosed while the brake operating member is not in operation, when the diagnosis is effected while the vehicle running speed is lower than the first threshold value.
The vehicle speed detecting device may be adapted to obtain the vehicle running speed on the basis of the rotating speed of the output shaft of a drive power source which drives the vehicle, or alternatively, on the basis of the rotating speeds of the vehicle wheels.
(3) A diagnosing apparatus according to the above mode (1) or (2), further comprising: a ready-state detecting device for determining whether an automotive vehicle on which the hydraulically operated braking system is provided is ready for running, or not; and a braking operation detecting device for determining whether the brake operating member is in operation or not, and wherein said diagnosing device includes a determining portion operable to determine whether the pressurizing device is abnormal or not, on the basis of the hydraulic pressure detected when said brake operation detecting device detects for the first time that the brake operating member is in operation, after the ready-state detecting device has detected that the automotive vehicle becomes ready for running.
In the diagnosing apparatus according to the above mode (3), the pressurizing device is diagnosed upon first detection that the brake operating member is not in operation after, the automotive vehicle becomes ready for running. Where the brake operating member is not in operation at the time when the automotive vehicle has become ready for running, the diagnosis of the pressurizing device is effected immediately after the vehicle has become ready for running. Where the brake operating member is already in operation when the automotive vehicle has become ready for running, the diagnosis is effected when a first operation of the brake operating member is detected after the vehicle has become ready for running.
The vehicle may be made ready for running as a result of an operation of a given operator-controlled member, or when a predetermined condition of the vehicle is satisfied. The operator-controlled member may be a main power switch, which may be an ignition switch operated by an ignition key, for starting a vehicle drive power source such as an engine. The predetermined condition of the vehicle may be a condition in which a load acting on the vehicle operator""s seat is larger than a predetermined upper limit.
(4) A diagnosing apparatus according to any one of the above modes (1)-(3), wherein the hydraulic pressure detecting device is connected to a fluid passage provided to delivery a fluid pressurized by the pressurizing device to an actuator of the hydraulically operated system, the diagnosing apparatus further comprising: a fluid communication regulating device provided in a portion of the fluid passage between the hydraulic pressure detecting device and the actuator, and having an open state for non-restricted fluid communication between the pressurizing device and the actuator, and a restricted state for restricted fluid communication between the pressurizing device and the actuator, and wherein the diagnosing device includes a restricted-state determining portion operable to determine whether the pressurizing device is abnormal or not, on the basis of the hydraulic pressure detected while the fluid communication regulating device is placed in the restricted state.
The fluid communication regulating device is selectively placed in the open state for non-restricted fluid communication between the pressurizing device and the actuator, or in the restricted state for restricted fluid communication between the pressurizing device and the actuator. The restricted state may be a closed state for complete disconnection of the pressurizing device from the actuator, or a throttling state for partial restriction of fluid flows between the pressurizing device and the actuator.
While the fluid communication regulating device is placed in the open state, the fluid pressurized by the pressurizing device is supplied to the actuator. While the fluid communication regulating device is placed in the restricted state, the supply of the fluid pressurized by the pressurizing device to the actuator is restricted. The pressure of the fluid as pressurized by the pressurizing device can be detected by the hydraulic pressure detecting device with a higher degree of accuracy when the fluid communication regulating device is placed in the restricted state, than in the open state. In particular, an increase in the pressure of the fluid as pressurized by the pressurizing device can be detected without an influence of the actuator, when the pressure is detected while the fluid communication regulating device is placed in the closed state in which the pressurizing device is disconnected from the actuator. Namely, the hydraulic pressure detected by the hydraulic pressure detecting device accurately represents the fluid pressure as pressurized by the pressurizing device.
The actuator may be a wheel brake cylinder for operating a wheel brake for braking a wheel of the vehicle. The wheel brake cylinder need not be operated with the fluid pressurized by the pressurizing device while the brake operating member is not in operation. Accordingly, the complete disconnection of the pressurizing device from the wheel brake cylinder does not cause any inconvenience while the brake operating member is in the non-operated position.
The fluid communication regulating device may be provided exclusively for the purpose of diagnosing the pressurizing device, or may be a control valve provided for other purposes, such as a pressure control device provided for controlling the fluid pressure in the actuator.
(5) A diagnosing apparatus according to any one of the above modes (1)-(4), further comprising a first terminating device for terminating an operation of the diagnosing device when the brake operating member is operated during the operation of the diagnosing device.
If the diagnosis of the pressurizing device is continued by the diagnosing device even after the brake operating member is operated, the diagnosing device may suffer from an erroneous determination as to whether the pressurizing device is abnormal or not. To avoid this erroneous determination, the first terminating device terminates an operation of the diagnosing device when the brake operating member is operated. The first terminating device is therefore effective to improve the reliability or accuracy of the diagnosis.
(6) A diagnosing apparatus according to any one of the above modes (2)-(5), further comprising a second terminating device for terminating an operation of the diagnosing device when the running speed of the automotive vehicle detected by the vehicle speed detecting device has exceeded a predetermined second threshold value during the operation of the diagnosing device.
After the vehicle speed has exceeded the second threshold value, there is a risk that the brake operating member is operated during the diagnosis by the diagnosing device. In view of this risk, it is desirable to terminate the diagnosis when the vehicle speed has exceeded the second threshold value. It is also desirable to terminate the diagnosis for improving the safety of running of the vehicle.
The second threshold value may be equal to the first threshold value indicated above, or higher than the first threshold value.
(7) A diagnosing apparatus according to any one f the above modes (1)-(6), wherein the diagnosing device determines that the pressurizing device is abnormal, when the hydraulic pressure detected by the hydraulic pressure detecting device is lower than a threshold value determined by an operating condition of the pressurizing device.
In the diagnosing apparatus according to the above mode (7), the diagnosing device determines that the pressurizing device is abnormal, when the hydraulic pressure detected while the brake operating member is not in operation and while the pressurizing device is in operation is lower than the predetermined threshold value.
Where the pressurizing device is operated in a predetermined operating condition during the diagnosis thereof, the threshold value of the hydraulic pressure detected by the hydraulic pressure detecting device may be a predetermined fixed value. Where the operating condition of the pressurizing device during its diagnosis varies from time to time, the threshold value may be determined depending upon the operating condition of the pressurizing device.
(8) A diagnosing apparatus according to the above mode (7), wherein the diagnosing device includes a threshold determining device for determining the threshold value of the hydraulic pressure depending upon the operating condition of the pressurizing device.
The threshold determining device may be considered to include hydraulic pressure estimating means for estimating a pressure of the fluid pressurized by the pressurizing device, depending upon the operating condition of the pressurizing device. For instance, the diagnosing device may determine that the pressurizing device is abnormal, if the hydraulic pressure actually detected by the hydraulic pressure detecting-device is lower than the threshold value which is determined by the estimated pressure of the fluid pressurized by the pressurizing device. Where the pressurizing device includes a pump and an electric motor for operating the pump, the threshold value of the hydraulic pressure may be determined on the basis of the electric current flowing through the electric motor or the rotating speed of the electric motor, which current or rotating speed is an operating condition of the pressuring device. Where a pressure control valve is provided for controlling the pressure of the fluid pressurized by the pressurizing device, the threshold value may be determined on the basis of the operating condition of the pressure control valve, such as the amount of electric current applied to a solenoid coil of the pressure control valve or the duty ratio of the pressure control valve.
(9) A diagnosing apparatus according to any one of the above modes (1)-(8), wherein the diagnosing device includes a pressurizing-device control device for controlling the pressurizing device such that the pressurizing device is operated in a predetermined operating condition.
(10) A diagnosing apparatus according to any one of the above modes (1)-(9), wherein the diagnosing device determines whether the pressurizing device is abnormal or not, depending upon whether the brake operating member is operated within a predetermined time after the fluid communication regulating device is operated from the restricted state to the open state.
In the diagnosing apparatus according to the above mode (10), a brake operation detecting device may be provided for determining whether the brake operating member is in operation or not, such that the brake operating detecting device determines that the brake operating member is operated when an amount of operation of the brake operating member has exceeded a predetermined value. In this case, the fluid communication regulating device has a closed state as the restricted state, in which the pressurizing device is disconnected from the actuator. While the pressurizing device is disconnected from the actuator, the application of an operating force to the brake operating member may not cause the amount of operation of the brake operating member to exceed the predetermined value. In this event, the brake operating detecting device may determine that the brake operating member is not in operation while the brake operating member is in fact in operation. In view of this, it is reasonable to consider that when the brake operating member is operated within the predetermined time after the fluid communication regulating device is operated to the open state, the brake operating member was in operation even if the brake operation detecting device had once determined that the brake operating member was not in operation.
In the above case, the hydraulic pressure detected by the hydraulic pressure detecting device is considered to be the fluid pressure generated by operation of the brake operating member, and therefore the pressurizing device may be considered abnormal, even if the detected hydraulic pressure is higher than a predetermined threshold value above which the pressurizing device is considered normal.
The hydraulic pressure may be detected by the hydraulic pressure detecting device while the brake operating member is in operation. In this case, the detected hydraulic pressure is a sum of the first fluid pressure generated by an operation of the brake operating member and the second fluid pressure generated by an operation of the pressurizing device. This sum is compared with a predetermined nominal value of the sum which is estimated to be established while the pressurizing device is normal and while the brake operating member is operated with a predetermined operating force. In this case, the diagnosing device may determine that the pressurizing device is normal, when the detected sum is larger than the predetermined nominal value.
It is also possible that the diagnosing device does not determine whether the pressurizing device is abnormal or not, namely, the diagnosing device does not diagnose the pressurizing device, if the brake operating member is operated after the fluid communication regulating device is operated to the open state, since the hydraulic pressure detected by the hydraulic pressure detecting device includes the first fluid pressure generated by operation of the brake operating member.
(11) A diagnosing apparatus according to the above mode (10), wherein the fluid communication regulating device is provided in a portion of the fluid passage which connects the actuator and a master cylinder which is operatively connected to the brake operating member and which generates a fluid pressure corresponding to an operating condition of the brake operating member.
In the diagnosing apparatus according to the above mode (11), the fluid passage described above with respect to the diagnosing apparatus according to the above mode (10) has a portion which connects the actuator and the master cylinder and in which the fluid communication regulating device is provided. In the present embodiment, the hydraulic pressure detecting device is disposed so as to detect the fluid pressure in the above-indicated portion of the fluid passage.
While the fluid communication regulating device is placed in its restricted state, the application of the fluid pressure generated by the master cylinder to the actuator is restricted by the fluid communication regulating device, so that an operating force acting on the brake operating member may not cause an increase in the amount of operation (operating stroke) of the brake operating member by an amount exceeding a given threshold above which the brake operating member is considered to have been operated. When the fluid communication regulating device is switched to its open state, the fluid pressurized by the master cylinder can be supplied to the actuator through the regulating device in the open state, so that the amount of operation of the brake operating member exceeds the given threshold. The present arrangement is particularly effective where the fluid communication regulating device has a closed state, like a shut-off valve. In this closed state in which the hydraulic pressure is detected, the master cylinder is completely disconnected from the actuator, an operating force acting on the brake operating member will not cause the amount of operation of the brake operating member to increase by an amount exceeding the above-indicated threshold.
(12) A diagnosing apparatus according to any one of the above modes (4)-(11), wherein said diagnosing device includes a regulating device control device operable to operate the fluid communication regulating device from the restricted state to said open state when the hydraulic pressure detected by the hydraulic pressure detecting device indicates that the pressurizing device is normal.
In the diagnosing apparatus according to the above mode (12), the regulating-device control device operates the fluid communication regulating device to be placed in the open state, when the detected hydraulic pressure indicates that the pressurizing device is normal, for instance, when the detected hydraulic pressure is higher than the predetermined threshold value described above with respect to the above mode (7). In this respect, it is noted that when the detected hydraulic pressure indicates that the pressurizing device is abnormal, for instance, when the detected hydraulic pressure is lower than the predetermined threshold value indicated above, it is not necessary to check if the brake operating member was in operation when the hydraulic pressure was detected.
(13) A diagnosing apparatus according to any one of the above modes (1)-(12), wherein the diagnosing device determines whether the pressuring device is abnormal or not, on the basis of a plurality of values of the hydraulic pressure which are obtained by the hydraulic pressure detecting device when the pressurizing device is operated in respective different operating conditions.
In the diagnosing apparatus according to the above mode (13), the diagnosing device diagnoses the pressurizing device, on the basis of a plurality of hydraulic pressure values detected when the pressurizing device is operated in the respective different operating conditions, that is, on the basis of the two or more relationships between the different operating conditions of the pressurizing device and the hydraulic pressure values detected in the respective different operating conditions of the pressurizing device. This arrangement using the two or more hydraulic pressure values assures a higher degree of accuracy of the diagnosis of the pressuring device, than the arrangement using a single hydraulic pressure value.
The hydraulic pressure value or values detected by the hydraulic pressure detecting device while the brake operating member is not in operation corresponds to the specific operating condition of the pressurizing device. The operating condition of the pressurizing device is considered to be an output of the pressurizing device, which is determined by an input to the pressurizing device, which in turn is controlled by a control device. In the present diagnosing apparatus, therefore, it is possible to determine whether the relationship between the output and input of the pressurizing device is normal or not.
(14) A diagnosing apparatus according to the above mode (13), wherein said diagnosing device includes a first control portion for operating the pressurizing device in a predetermined first operating condition, and a second control portion for operating the pressurizing device in a predetermined second operating condition different from the predetermined first operating condition.
The diagnosing device may include more than three control portions including the first and second control portions indicated above. For instance, the diagnosing device includes a third and a fourth control portion as well as the first and second control portions.
Each diagnostic determination of the pressurizing device; may be based on the hydraulic pressure values detected during operations of the pressurizing device whose operating conditions are controlled by the respective two or more control portions. Alternatively, the control portions for controlling the operating conditions of the pressurizing device in one diagnostic determination of the pressurizing device may be different from those for controlling the operating conditions in another diagnostic determination of the pressurizing device.
(15) A diagnosing apparatus according to the above mode (13) or (14), wherein the diagnosing device includes a pressure data memory for storing values of the hydraulic pressure detected by the hydraulic pressure detecting device in the respective different operating conditions of the pressurizing device, the diagnosing device effecting diagnostic determinations at different times as to whether the pressurizing device is abnormal or not, such that a present one of the diagnostic determinations is effected on the basis of the plurality of values of the hydraulic pressure at least one of which is stored in the pressure data memory and was detected in another of the diagnostic determinations during an operation of the pressurizing device in the operating condition different from the operating condition in which the pressurizing device is operated to effect the present one of the diagnostic determinations.
Where the hydraulic pressure values are detected during operations of the pressuring device in different operating conditions to effect each diagnostic determination as to whether the pressure device is normal or not, each diagnostic determination requires a comparatively long time. In the diagnosing apparatus according to the above mode (15), the present diagnostic determination is effected on the basis of the two or more hydraulic pressure values at least one of which is stored in the pressure data memory and was detected for another diagnostic determination during an operation of the pressurizing device in the operating condition different from the operating condition in which the pressurizing device is operated to effect the present diagnostic determinations. The present diagnostic apparatus requires a reduced time for effecting each diagnostic determination.
For instance, the pressurizing device is operated in two different operating conditions alternately to effect the two successive diagnostic determinations. In this case, the present diagnostic determination is made on the basis of the hydraulic pressure value detected for the last diagnostic determination and the hydraulic pressure value detected for the present diagnostic determination. Further, the plurality of values of the hydraulic pressure used for each diagnostic determination may include a hydraulic pressure value detected for a purpose other than the diagnostic purpose. In any case, it is desirable that the detected hydraulic pressure values be stored in the pressure data memory in relation to the operating conditions of the pressurizing device in which the hydraulic pressure values were detected.
(16) A diagnosing apparatus according to any one of the above modes (1)-(15), wherein the diagnosing device includes at least one of (a) a first determining portion operable to determine whether the pressurizing device is abnormal or not, on the basis of the hydraulic pressure detected by the hydraulic pressure detecting device while the pressurizing device is not in operation, and (b) a second determining portion operable to determine whether the pressurizing device is abnormal or not, on the basis of the hydraulic pressure detected by the hydraulic pressure detecting device while the brake operating member is in operation.
According to diagnosing apparatus according to the above mode (16), the pressurizing apparatus can be diagnosed on the basis of at least one of results of three diagnostic determinations which are effected (i) while the brake operating member is not in operation and while the pressurizing device is in operation, (ii) while the brake operating member and the pressurizing device are both in operation, and (iii) while the brake operating member is in operation and while the pressurizing device is not in operation. The diagnosing device may finally determine that the pressurizing device is abnormal, if any one of the three diagnostic determinations (i), (ii) and (iii) indicates an abnormality of the pressurizing device, or if the determinations (i) and (ii) or (iii) indicate an abnormality of the pressurizing device.
Thus, the apparatus according to the above mode (16) is capable of diagnosing the pressurizing device in a plurality of different conditions of the braking system, assuring an improved accuracy of the diagnosis and permitting a detailed analysis regarding the abnormality visavis the specific operating condition of the braking system.
(17) A diagnosing apparatus according to any one of the above modes (1)-(16), wherein the diagnosing device includes a multiple phase determining portion for determining whether the pressurizing device is abnormal or not, on the basis of at least two relationships each of which is a relationship among at least two physical quantities selected from the group consisting of a quantity indicative of an operating condition of said pressurizing device; the hydraulic pressure detected by the hydraulic pressure detecting device; and a deceleration value of an automotive vehicle on which the hydraulically operated braking system is provided.
In the diagnosing apparatus according to the above mode (17), the diagnosis of the pressurizing device is based on at least two relationships selected from the following four relationships: a relationship between the detected hydraulic pressure and the quantity indicative of the operating condition of the pressurizing device; a relationship between the detected hydraulic pressure and the vehicle deceleration value; a relationship among the detected hydraulic pressure, the quantity indicative of the operating condition and the vehicle deceleration value; and a relationship between the quantity indicative of the operating condition and the vehicle deceleration value.
While the brake operating member is not in operation and while the pressurizing device is in operation, each of the above indicated four relationships among the physical quantities is known. For instance, the quantity indicative of the operating condition of the pressurizing device (which quantity is considered an input of the pressurizing device) and the detected hydraulic pressure generated by the pressurizing device (witch pressure is considered an output of the pressurizing device) have a known nominal or desired relationship. While the braking system is operated with an operation of the pressurizing device, the deceleration value of the vehicle increases with an increase in the pressure of the fluid pressurized by the pressurizing device, that is, with an increase in the detected hydraulic pressure. Accordingly, the pressurizing device can be diagnosed on the basis of the at least two relationships among the at least two physical quantities selected from the three physical quantities indicated above.
Where the actuator described above with respect to the above mode (14) is a wheel brake cylinder for operating a wheel brake for braking a vehicle wheel, the fluid communication regulating device is preferably placed in the open state when the pressurizing device is diagnosed on the basis of the above indicated relationships. In this respect, it is noted that the pressurized fluid is preferably supplied to the wheel brake cylinder, in order to detect the vehicle deceleration value.
(18) A diagnosing apparatus for diagnosing a pressurizing device provided in a hydraulically operated braking system operated by a brake operating member, the diagnosing apparatus comprising:
a hydraulic pressure detecting device operable to detect a hydraulic pressure which is a sum of a first fluid pressure generated by an operation of the brake operating member and a second fluid pressure generated by an operation of the pressurizing device; and
a diagnosing device operable to determine whether the pressurizing device is abnormal or not, on the basis of at least two hydraulic pressures selected from the group consisting of (a) the hydraulic pressure detected the hydraulic pressure detecting device while the brake operating member is not in operation and while the pressurizing device is in operation, (b) the hydraulic pressure detected by the hydraulic pressure detecting device while the brake operating member and the pressurizing device are both in operation, and (c) the hydraulic pressure detected by the hydraulic pressure detecting device while the brake operating member is in operation and while the pressurizing device is not in operation.
The diagnosing apparatus according to the above mode (18) of this invention may further include a feature according to any one of the above modes (1)-(17).
(19) A diagnosing apparatus for diagnosing a pressurizing device provided in a hydraulically operated system operated by a brake operating member, the diagnosing apparatus comprising:
a hydraulic pressure detecting operable to detect a hydraulic pressure which is a sum of a first fluid pressure generated by an operation of the brake operating member and a second fluid pressure generated by an operation of the pressurizing device; and
a diagnosing device operable to determine whether the pressurizing device is abnormal or not, on the basis of at least two relationships each of which is a relationship among at least two physical quantities selected from the group consisting of: a quantity indicative of an operating condition of the pressurizing device; the hydraulic pressure detected by the hydraulic pressure detecting device; and a deceleration value of an automotive vehicle on which the hydraulically operated braking system is provided.
The operating condition of the pressuring device indicated above includes the non-operated state as well as the operated state. The hydraulic pressure and the deceleration value indicated above may be detected while the brake operating member is in operation or while it is not in operation, and while the pressurizing device is in operation or while it is not in operation.
The diagnosing apparatus according to the above mode (19) may further includes a feature according to any one of the above modes (1)-(18).
(20) A diagnosing apparatus according to any one of the above modes (1)-(19), wherein the hydraulically operated braking system has a plurality of fluid passages extending from the pressurizing device, and the hydraulic pressure detecting device includes a plurality of pressure sensors connected to the plurality of fluid passages, respectively, the diagnosing device determining whether said pressuring device is abnormal or not, on the basis of a difference between values of the hydraulic pressure detected by said plurality of pressure sensors.
In the diagnosing apparatus according to the above mode (20), the pressure detecting device includes two or more pressure sensors, and the diagnosing device is arranged to diagnose the pressurizing device also on the basis of a difference of the two or more values of the hydraulic pressure detected by the two or more pressure sensors. This arrangement assures a higher degree of accuracy of diagnosis of the pressurizing device, than the arrangement wherein the diagnosis is made on the basis of the hydraulic pressure detected by a single pressure sensor.
Where the braking system is adapted such that the fluid pressures in the plurality of fluid passages are equal to each other, the pressurizing device is considered to be abnormal if the difference of the hydraulic pressure values detected by the plurality of pressure sensors is larger than a predetermined threshold. Where the braking system is adapted such that the fluid pressures in the fluid passages have a predetermined nominal difference, the pressurizing device is considered to be abnormal if the difference of the hydraulic pressure values detected by the pressure sensors is larger than the predetermined nominal difference by more than a predetermined amount.
The pressurizing device may have a single pressurizing portion or a plurality of pressurizing portions. Where the fluid passages extend from the plurality of pressurizing portions, at least one of the pressurizing portions is considered to be abnormal, if the hydraulic pressure values detected by the respective pressure sensors provided for the respective fluid passages have a difference larger than a predetermined threshold, while the pressurizing portions are operated in the same operating condition.
The pressuring device may include a single pressurizing portion from which a plurality of fluid passages extend, and a plurality of fluid communication regulating devices which are connected to respective fluid passages and each of which has an open state for non-restricted fluid flows through the corresponding fluid passage and a restricted state for restricted fluid flows through the corresponding fluid passages. If a difference of the hydraulic pressure values detected by the pressure sensors while the fluid communication regulating devices are placed in the restricted state is larger than a predetermined threshold, at least one of the fluid communication regulating devices is considered to be abnormal.
(21) A diagnosing apparatus for diagnosing a first pressuring device and a second pressurizing device provided in a hydraulically operated braking system which includes (1) a master cylinder having two pressurizing chambers and operable by a brake operating member to generate in the two pressurizing chambers a hydraulic pressure corresponding to an operating force acting on the brake operating member, (2) a first group of brake cylinders connected to a first fluid passage extending from one of the two pressurizing chambers, and a second group of brake cylinders connected to a second fluid passage extending from the other of the two pressurizing chambers, and (3) the first and second pressurizing devices operable to deliver a pressurized fluid through the first and second fluid passages, respectively, while the brake operating member is not in operation, characterized by comprising:
a first and a second pressure detecting device connected to the first and second fluid passages, respectively; and
a diagnosing device operable to determine whether at least one of the first and second pressurizing devices is abnormal or not, on the basis of a difference between hydraulic pressure values detected by the first and second hydraulic pressure detecting devices while the brake operating member is not in operation and while the first and second pressurizing devices are operated in the same operating condition.
Where the hydraulically operated braking system is an automotive vehicle braking system of diagonal or X-cross type having two brake application sub-systems, the first group of brake cylinders consists of a front right wheel brake cylinder and a rear left wheel brake cylinder for braking a front right wheel and a rear left wheel of the vehicle, respectively, while the second group of brake cylinders consists of a front left wheel brake cylinder and a rear right wheel brake cylinder for braking a front left wheel and a rear right wheel of the vehicle, respectively. The first hydraulic pressure detecting device is connected to the first fluid passage which connects the first group of brake cylinders to one of the two pressurizing chambers of the master cylinder, while the second hydraulic pressure detecting device is connected to the second fluid passage which connects the second group of brake cylinders and the other pressurizing chamber. In the diagonal type braking system, the hydraulic pressures in the first and second fluid passages are normally equal to each other. If a difference between the hydraulic pressures in the first and second fluid passages is larger than a predetermined threshold value, at least one of the first and second pressurizing devices is considered to be abnormal.
The diagnosing apparatus according to the above mode (21) may include a feature according to any one of the above modes (1)-(29).
(22) A diagnosing apparatus according to any one of the above modes (1)-(21), wherein the pressurizing device (or each of the first and second pressurizing devices) includes a pump for pressurizing a working fluid, and a pump motor for operating the pump.
As described in detail in the DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS, the pump may be adapted to pressurize the fluid stored in or delivered from the master cylinder, or alternatively pump up the fluid from a reservoir which stores the fluid at the atmospheric pressure.
In the diagnosing apparatus according to the above mode (22), the operating condition of the pressurizing device is determined by the operating condition of the pump, which can be controlled by controlling the operating condition of the pump motor
(23) A diagnosing apparatus according to any one of the above modes (1)-(22), wherein the pressurizing device (each of the first and second pressurizing devices) includes a solenoid-operated pressure control valve for controlling a pressure of a working fluid pressurized by the pressurizing device.
In the diagnosing apparatus according to the above mode (23), the operating condition of the pressurizing device is determined by the operating condition of the solenoid-operated pressure control valve, and can be controlled by controlling an electric current applied to a solenoid coil of the pressure control valve.
(24) A diagnosing apparatus for diagnosing a pressurizing device provided in a hydraulically operated braking system which is operated by a brake operating member and which includes a master cylinder having a pressurizing piston which is advanced by a drive force produced by the pressurizing device and an operating force applied to the brake operating member and which partially defines a pressurizing chamber, the diagnosing apparatus comprising:
a master cylinder pressure detecting device operable to detect a hydraulic pressure in the pressurizing chamber of the master cylinder; and
a diagnosing device operable to determine whether the pressurizing device is abnormal or not, on the basis of the hydraulic pressure detected by the master cylinder pressure detecting device while the brake operating member is not in operation and while the pressurizing device is in operation.
The diagnosing apparatus according to the above mode (24) will be described in detail as the first embodiment of this invention in the DESCRIPTION OF THE PREFERRED EMBODIMENTS. While the brake operating member is not in operation, no operating force of the brake operating member is applied to the pressurizing piston of the master cylinder, and only the drive force based on the fluid pressure generated by the pressurizing device is applied to the pressurizing piston, so that the fluid pressure in the pressurizing chamber of the master cylinder corresponds to the drive force produced by the pressurizing device.
The master cylinder pressure detecting device may be adapted to directly detect the pressure of the fluid in the pressurizing chamber of the master cylinder, or detect the fluid pressure at a portion of the braking system which communicates with the pressurizing chamber.
The diagnosing apparatus according to the above mode (24) may include a feature according to any one of the above modes (1)-(23).
(25) A diagnosing apparatus according to the above mode (24), wherein the pressurizing piston of the master cylinder partially define a front pressurizing chamber as the pressurizing chamber on one of opposite sides thereof, and a rear pressurizing chamber on the other of the opposite sides thereof, the pressurizing device being connected to the rear pressurizing chamber.
When the brake operating member is operated, the pressurizing piston is advanced to increase the fluid pressure in the front pressurizing chamber. When the pressurizing device is operated, the fluid pressure in the rear pressurizing chamber is increased, so that the pressurizing piston is advanced to increase the fluid pressure in the front pressurizing chamber. Accordingly, the fluid pressure in the front pressuring chamber is a sum of the fluid pressure generated by an operation of the brake operating member and the fluid pressure generated by an operation of the pressurizing device.
(26) A diagnosing apparatus for diagnosing a pressurizing device provided in a hydraulically operated braking system which is operated by a brake operating member and which includes a master cylinder adapted to generate a hydraulic pressure corresponding to an operating force acting on said brake operating member, the pressurizing device being operable to pressurize a working fluid received from the master cylinder so that the pressurized fluid is delivered through a fluid passage extending from the master cylinder, the diagnosing apparatus comprising:
a hydraulic pressure detecting device connected to the fluid passage;
a fluid communication regulating device provided in the fluid passage and having an open state for non-restricted fluid communication of the hydraulic pressure detecting device and the pressurizing device with the master cylinder, and a restricted state for restricted fluid communication of the hydraulic pressure detecting device and the pressurizing device with the master cylinder; and
a diagnosing device operable to determine whether the pressurizing device is abnormal or not, on the basis of a hydraulic pressure detected by the hydraulic pressure detecting device while the brake operating member is not in operation, while the fluid communication regulating device is placed in the restricted state, and while the pressurizing device is in operation.
The diagnosing apparatus according to the above mode (26) will be described in detail as the fourth and fifth embodiments of the invention in the DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS. While the brake operating member is not in operation, no fluid pressure is generated in the master cylinder by the brake operating member. In this condition, the pressure of the fluid in the master cylinder which is to be pressurized by the pressurizing device is substantially equal to the atmospheric pressure. Accordingly, the hydraulic pressure detected by the hydraulic pressure detecting device is the pressure which corresponds to the operating condition of the pressurizing device.
While the fluid communication regulating device is placed in the restricted state, the fluid communication of the hydraulic pressure detecting device and the pressurizing device with the master cylinder is restricted while no fluid pressure is generated by the master cylinder by the brake operating member, so that the flow of the pressurized fluid from the pressurizing device to the master cylinder is restricted. Accordingly, the hydraulic pressure as detected by the hydraulic pressure detecting device accurately represents the operating condition of the pressurizing device, whereby the reliability or accuracy of diagnosis of the pressurizing device is improved. While the fluid communication regulating device is placed in the closed state, the flow of the pressurized fluid from the pressurizing device to the master cylinder is inhibited, so that the accuracy of the diagnosis cam be further improved. The closed state is considered as one form of the restricted state.
The diagnosing apparatus according to the above mode (26) may include a feature according to any one of the above modes (1)-(25).
(27) A diagnosing apparatus for diagnosing a pressurizing device provided in a hydraulically operated braking system which includes a brake operating member and a master cylinder adapted to generate a hydraulic pressure corresponding to an operating force acting on the brake operating member, the pressurizing device being operable to pressurize a working fluid so that the pressurized fluid is delivered through a fluid-passage extending from the master cylinder, characterized by comprising:
a hydraulic pressure detecting device connected to the fluid passage;
a fluid communication regulating device provided in the fluid passage and having an open state for non-restricted fluid communication of the hydraulic pressure detecting device and the pressurizing device with the master cylinder, and a restricted state for restricted fluid communication of the hydraulic pressure detecting device and the pressurizing device with the master cylinder; and
a diagnosing device operable to determine whether the pressurizing device is abnormal or not, on the basis of a hydraulic pressure detected by the hydraulic pressure detecting device while the brake operating member is not in operation, while the fluid communication regulating device is placed in the restricted state, and while the pressurizing device is in operation.
In the diagnosing apparatus according to the above mode (27), the pressurizing device may be adapted to pressurize the fluid received from the master cylinder or from a reservoir which stores the fluid at a pressure substantially equal to the atmospheric pressure, or pressurize the fluid received from a selected one of the master cylinder and the reservoir. In any of the above cases, the pressurizing device is diagnosed on the basis of the hydraulic pressure detected by the hydraulic pressure detecting device while the brake operating member is not in operation.
The pressurizing device may be connected to the pressurizing chamber of the master cylinder so that the fluid pressurized by the pressurizing chamber is delivered through the pressurizing chamber of the master cylinder and the fluid passage. Alternatively, the pressurizing chamber may be connected directly to the fluid passage so that the fluid pressurized by the pressurizing device is delivered through the fluid passage, without passing the pressurizing chamber.
The diagnosing apparatus according to the above mode (27) may include a feature according to any one of the above modes (1)-(25).
(28) A hydraulically operated braking system comprising:
a pressurizing device for delivering a pressurized fluid to a brake cylinder;
a pressure control device including a control data memory which stores a nominal relationship between an operating condition of the pressurizing device and the pressure of the fluid pressurized by the pressurizing device, the pressure control device further including a control portion for controlling the pressurizing device according to the nominal relationship stored in the control data memory, to thereby control the pressure in the brake cylinder; and
a diagnosing apparatus operable to determine whether the pressurizing device is abnormal or not, on the basis of pressure values of the fluid pressurized by the pressurizing device, which pressure values are detected while the pressurizing device is operated in a plurality of different operating conditions, and wherein the pressure control device includes a control data compensating portion operable when the diagnosing apparatus determines that the pressurizing device is normal, the control data compensating portion compensating the nominal relationship on the basis of the pressure values detected by the hydraulic pressure detecting device when the diagnosing apparatus has determined that the pressurizing device is normal.
In the hydraulically operated braking system according to the above mode (28) of this invention, the stored nominal relationship between the operating condition of the pressurizing device and the pressure of the fluid pressurized by the pressurizing device is compensated on the basis of the pressure values detected when the diagnosing apparatus has determined that the pressurizing device is normal. The pressure of the fluid pressurized by the pressurizing device operated in a given operating condition may vary due to a chronological change and the operating environment of the pressurizing device. In the present braking system, the control data compensating portion of the pressure control device is effective to reduce a variation in the fluid pressure generated by the pressurizing device for thereby reducing the deterioration of control accuracy of the braking pressure of the brake cylinder, since the control data compensating portion is adapted to compensate or the presently stored nominal relationship between the operating condition and the output pressure of the pressurizing device on the basis of the pressure values detected upon determination that the pressurizing device is normal,